Python 3 Programming Tutorial - Matplotlib Labels and titles

Key Takeaways

hello everybody and welcome to the second part of our map plot lib miniseries in Python 3 in the last video we showed how to do a very basic plot of X and Y uh we hardcoded the values in there and in this video I'd like to show you guys um that you don't have to do that how do you get around that and then also we'll show some labels and then also an error that you might see and not understand what that means so with that let's go ahead and get started so pt. plot generally um in your script you're going to be plotting VAR like values uh that you're assigning to variables that you're getting from some sort of source so you might have um you know a source online a database a CSV file um something like that and then you're going to be pulling those and then putting them as a list into a variable so you're usually going to have a x and a y and then uh X and Y will equal something and in our case we're just going to say they equal a list and now what we can do is just copy and paste uh these values basically into our list so that was our X and our Y and then here you just plot x y and that's really all there is to it there so then um we can save and run that and we get you know our graph that we saw before so you know nothing's really changed um so now what we can do though is if you paid attention in school you know that you have to include titles and labels to everything okay so this is a bad chart so how do we add titles and labels we have pt. tile and this will add a title to the Chart uh we'll just call it epic chart and then we have PLT doy label um and then this we can just I don't know y AIS and then p L t.x label and we'll call this xaxis so we'll save and run that and now we can see we've given our chart a nice title y label and an X label okay let's close that close this now finally the last thing I just want to show you guys is the X and Y here uh we're assuming that we've have we have some sort of function that's or a class or something that's come through and populated these values again we've card coded it here but normally probably wouldn't you'd have some something assigning values to these variables so sometimes the following happens and you get this error value error X and Y must have the same First Dimension now the first time I saw this error I had no idea what the heck that meant X and Y must have the same for what like what does that even mean you know and so maybe like the First Dimension is length I don't I have no idea but anyway you have that any time you're plotting obviously we've got more X's than we have y's so it goes to plot X and then it has no y to match and so we get in a little bit of trouble here so um so whenever you see that error just know that that's what's happening so usually what I the next thing I'll do whenever something like that happens is either I'll look at the code and spot what what has happened or you can always print Len X and then basically copy paste print l y and then um you could even do this right let's add back our zero save and run that and before we get to this error that says that we can see up here well we've got a five and a four we printed X first and we can see here that oh yeah X has five values y only has four so now we need to consult our code and figure out what we've done wrong um so anyway that's pretty common error at least that I see a lot um in my own code so anyway way um so that's that that's that little error how to add labels and then also plot plot variables which um not not too not too confusing so the next thing that I wanted to cover is uh let's save and run this one more time you know this chart I mean as epic chart as it is uh it's pretty boring looking chart and so there's a couple of things that we can do one we can go through and we can customize everything ourselves or we can um uh in the code rather you can customize everything or we can use what are called Styles um which is kind of a new addition to map plot lib and we can use these styles to kind of store specific formats to charts um that we want so anyway that's what we're going to be covering in the next uh video is Styles and so that'll help you make very quick decent looking charts and then you can further customize later on if you want uh but anyway that's what we'll be talking about in the next video is Styles if you guys have any questions or comments on this video feel free to leave them below as always thanks for watching thanks for all the support and subscriptions and until next time